title: Characterization and crystal structure of lysine insensitive Corynebacterium glutamicum dihydrodipicolinate synthase (cDHDPS) protein.
abstract: The lysine insensitive Corynebacterium glutamicum dihydrodipicolinate synthase enzyme (cDHDPS) was recently successfully introduced into maize plants to enhance the level of lysine in the grain. To better understand lysine insensitivity of the cDHDPS, we expressed, purified, kinetically characterized the protein, and solved its X-ray crystal structure. The cDHDPS enzyme has a fold and overall structure that is highly similar to other DHDPS proteins. A noteworthy feature of the active site is the evidence that the catalytic lysine residue forms a Schiff base adduct with pyruvate. Analyses of the cDHDPS structure in the vicinity of the putative binding site for S-lysine revealed that the allosteric binding site in the Escherichia coli DHDPS protein does not exist in cDHDPS due to three non-conservative amino acids substitutions, and this is likely why cDHDPS is not feedback inhibited by lysine.
authors.affiliation: Monsanto Company, 800 North Lindbergh Boulevard, St. Louis, MO 63167, USA. elena.a.rice@monsanto.com
authors.forename: Elena A
authors.initials: EA
authors.lastname: Rice
authors.forename: Gary A
authors.initials: GA
authors.lastname: Bannon
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Glenn
authors.forename: Soon Seog
authors.initials: SS
authors.lastname: Jeong
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sturman
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Rydel
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D048230:Corynebacterium glutamicum / Q000201:enzymology*; D018360:Crystallography, X-Ray / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D006801:Humans; D006836:Hydro-Lyases / Q000737:chemistry*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008239:Lysine / Q000737:chemistry*; D008954:Models, Biological; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D006836:Hydro-Lyases; C020040:4-hydroxy-tetrahydrodipicolinate synthase; D008239:Lysine